This invention relates to the processing of printed documents. The processing of printed documents is far inferior today, compared with the sophisticated processing possible for electronic documents.
Despite numerous predictions of a ‘paperless world’, paper documents continue to play a pivotal role in business enterprises and government institutions, and there is a continuing need to process paper documents. As a result, there is often a translation from the digital domain to the paper domain and back from the paper domain (for example after document has been edited or used for verification purposes) to the digital domain.
The transition from the digital domain to the paper domain and back can result in a reduction in quality of the digitally stored image, and furthermore there is the possibility of tampering of documents. Printing and scanning operations can cause severe non-linear distortions, de-localization and lowpass filtering at the pixel level, which are not necessarily visible to the human eye. For example, the printed and scanned image of a paper document can have as high as 10%-30% of the pixels in error, even though visually the document appears similar to the electronic original document image.
There is therefore a need for an improved method and apparatus for processing printed documents.